The paper presents application of a modified, symmetrical Bouc-Wen model to simulate the mechanical behaviour of high-frequency piezoelectric actuators (PAs). In order to identify parameters of the model, a two-step algorithm was developed. In its first stage, the mechanical parameters were identified by taking into account their bilinear variability and using a square input voltage waveform. In the second step, the hysteresis parameters were determined based on a periodic excitation. Additionally, in order to reduce the influence of measurement errors in determination of selected derivatives the continuum wavelet transform (CWT) and translation-rotation transformation (TRT) methods were applied. The results proved that the modified symmetrical Bouc-Wen model is able to describe the mechanical behaviour of PAs across a wide frequency range.
The knowledge of the load in prestressed bolted connections is essential for the proper operation and safety of engineering structures. Recently, bolted joints have become an area of intensive research associated with non-destructive diagnostics, in particular in the context of wave propagation techniques. In this paper, a novel procedure of bolt load estimation based on the energy of Lamb wave signals was proposed. Experimental tests were performed on a single lap joint of two steel plates. Ultrasonic waves were excited and registered by means of piezoelectric transducers, while precise measurement of the bolt load was obtained by means of using the force washer transducer. Experimental tests were supported by the finite element method analysis based on Schoenberg’s concept. The results showed that the relationship between the bolt load and signal energy was strongly nonlinear and it depended on the location of acquisition points.
Early detection of potential defects and identification of their location are necessary to ensure safe, reliable and long-term use of engineering structures. Non-destructive diagnostic tests based on guided wave propagation are becoming more popular because of the possibility to inspect large areas during a single measurement with a small number of sensors. The aim of this study is the application of guided wave propagation in non-destructive diagnostics of steel bridges. The paper contains results of numerical analyses for a typical railway bridge. The ability of damage detection using guided Lamb waves was demonstrated on the example of a part of a plate girder as well as a bolted connection. In addition, laboratory tests were performed to investigate the practical application of wave propagation for a steel plate and a prestressed bolted joint.
O obecności kobiet w nauce, tym, co mogłoby wspomóc ich kariery naukowe, oraz planach Akademii Młodych Uczonych mówią przewodnicząca AMU w IV kadencji dr Anna Ajduk z Uniwersytetu Warszawskiego oraz wiceprzewodniczące dr Nicole Dołowy- -Rybińska z Instytutu Slawistyki PAN, dr hab. Monika Kędra, prof. Instytutu Oceanologii PAN, i dr hab. inż. Monika Kwoka, prof. Politechniki Śląskiej.
The presence of women in science, methods of supporting them in pursuing careers in science, and the Polish Young Academy’s plans are discussed by Dr. Anna Ajduk of the University of Warsaw, who is chair of the Polish Young Academy, and its three deputy chairs – Assoc. Prof. Nicole Dołowy-Rybińska from the PAS Institute of Slavic Studies, Assoc. Prof. Monika Kędra from the PAS Institute of Oceanology, and Assoc. Prof. Monika Kwoka of the Silesian University of Technology.